Process for preparing diadducts of hydrocarbylthiophosphoric acids

ABSTRACT

Sequential diadducts of methylacetylene are obtained in radical reactions with a dihydrocarbyl thiophosphoric acid and then with a hydrocarbon thiol. The order of addition is critical in obtaining novel compositions which are attractive as pesticides since their high effectiveness is coupled with a surprisingly low toxicity towards mammalians.

United States Patent [191 Mueller et al.

PROCESS FOR PREPARING DIADDUCTS 0F HYDROCARBYLTHIOPHOSPHORIC ACIDSInventors: Wolfgang H. Mueller, Karlsruhe,

Germany; Alexis A. Oswald, Mountainside, NJ.

Assignee: Esso Research and Engineering Company, Linden, NJ.

Filed: Dec. 10, 1969 Appl. No.: 884,046

Related US. Application Data Division of Ser. No. 541,135, April 8,1966, abandoned.

U.S. Cl. 260/968, 204/162, 204/162 HE, 260/932, 260/948, 260/949,260/957, 260/978, 424/216 Int. Cl. C07! 9/16, AOln 9/36 Field of Search260/948, 968

[ 1 June 26, 1973 [56] References Cited UNITED STATES PATENTS 2,952,7009/1960 Lorenz et al 260/948 Primary ExaminerLewis Gotts AssistantExaminer-Anton H. Sutto Att0rney-Chasan and Sinnock and John P. Corcoran[5 7 ABSTRACT 5 Claims, No Drawings PROCESS FOR PREPARING DIADDUCTS OFHYDROCARBYLTIIIOPHOSPHORIC ACIDS organic thiol to produce new mixeddiadducts of methylacetylene. These diadducts could not be made by knownprocesses. They have an unexpected advantage as pesticides overstructurally related thiophosphates by virtue of their reduced toxicitytowards mammalians.

The reaction between 0,0'-dihydrocarbyl thiophosphoric acids and avariety of unsaturated organic compounds is known to produce adducts ofthe unsaturate. Some of these adducts were found to possess propertieswhich make them suitable as lubricating oil additives and/or pesticides.This in turn stimulated interest in new, superior adducts, and novel,more selective methods of addition.

Pesticidal compounds formed by the free radical addition of 0,0'-dialkylthiophosphoric acids to aceytlenes are disclosed in US. Pat. No.3,067,232. The monoadducts of methylacetylene, i.e., S-propenyl dialkylthiophosphates, have been tested in the present invention for destroyinga variety of insect pests. However, the toxicity of these particularcompounds to warm-blooded animals, including humans, has been found tobe quite high. Thus, the use of such compounds as pesticidal agents isseverely restricted. It has 40 now been discovered that themonothiophosphoric acid esters, resulting from the addition of 0,0-dihydrocarbyl thiophosphoric acids to methylacetylene, can be furtherreacted with an organic thiol to produce novel, mixed diadducts ofmethylacetylene, having excellent pesticidal activity and a low level oftoxicity towards warm-blooded animals. Additionally, it has now beendiscovered that the monothiophosphoric acid esters, i.e., S-propenyldihydrocarbyl thiophosphates, can be prepared in significantly increasedyields; when a stoichiometric excess of the acid reagents is used, thusproviding a most efficient route to the mixed diadducts.

In accordance with this invention, monoadducts of methylacetylene may beobtained in high yields by reacting a stoichiometric excess of adihydrocarbyl thiophosphoric acid with methylacetylene under freeradical addition conditions. In a preferred embodiment, the monoadduct,i.e. S-propenyldihydrocarbylthiophosphate, is utilized to prepare novel,mixed, diadducts of methylacetylene by free radical addition of anorganic thiol.

In our copending patent application, U.S. Ser. No. 518,028 nowabandoned, it is disclosed that the use of excess dithiophosphoric acidresults in the formation of the diadduct of methylacetylene,

e.g.: 0(0): SII IICECCII;

(EXCESS II s CH3 5 the monoadduct forming only when equimolar amounts ofthe reactants are employed, e.g.:

()}? San IICECCH; (1(0 SzUH CII 1113 equimolar II Thus, it was believedthat the reaction of methylacetylene with excess monothiophosphoric acidwould similarly lead to formation of a diadduct. However, it has nowbeen discovered that the use of excess monothiophosphoric acid in thereaction with methylacetylene does not lead to the diadduct, but rather,leads to significantly increased yields of the monoadduct, e.g.:

""TROXYSH IICC'CTI; "(RUMFS CH=CII o d CH3 III excess Thus, themonoadduct of methylacetylene may now be prepared in yields which are atleast 50 percent greater than that previously thought possible.

While the methylacetylene monoadducts of dihydrocarbyl thiophosphoricacid are unreactive towards an excess of the acid, they react with anorganic thiolin a very specific manner:

Rom 's ou=ou Rs'ir nom son cusu H (3H3 i) 3113 Iv It is surprising thatthe resulting free radical type sequential adducts cannot be formed by areversed sequence of addition. If instead of the acid, the thiol isreacted at first with the methylacetylene, the subsequent additionoccurs in an ionic manner. As a result, mixed diadducts of a differenttype are formed as shown by the following reaction equations:

II on; 0

The novel sequential diadducts of the present invention, Type IV, werefound to be particularly and unexpectedly desirable for pesticidal use.When compared to pesticidal phosphate esters of somewhat similarstructure, they showed a relatively low level of toxicity towardswarm-blooded animals, i.e., a greater level of safety when used aspesticides. For example, the median lethal oral dose for the knowncommerical com pound Thiol-Systox,

is about 1.5 mg. per body kg. See page 343 of the monograph entitled DieEntwicklung neuer lnsektizider Phosphorsa'ure-Ester, by GerhardSchrader, which was published by Verlag Chemie Gmbh., Weinheim/Bergstr.,Germany in 1963. In contrast, our sequential methylacetylene diadduct ofclosely related structure,

has a median lethal oral dose of more than 75 mg per body kg. This meansthat our diadduct is about 50 times safer to use.

The methyl branching of the sequential adducts of the presentapplication is apparently reducing their toxicity towards mammalians. Itis important that the methyl branching of our adducts is on a B ratherthan on an a carbon atom relative to the thiophosphate moiety. Since allof our adducts have the a unsubstituted primary thiophosphate esterstructure, they are more stable than the secondary or tertiary esterstructures. From a practical viewpoint, this stability is veryimportant. For example, the hydrolytic stability is essential when thesecompounds are to be used as an aqueous emulsion for pesticidal sprayapplications.

The monoadduct of methylacetylene, i.e., S-propenyl dihydrocarbylthiophosphate, may be prepared by reacting methylacetylene with adihydrocarbyl thiophosphoric acid in the presence of a free radicalinitiator. In general, the type of thiophosphoric acids applicable tothis invention may be represented by the following formula:

Rr-O n) P- S II wherein R, and R when taken separately may each be aradical selected from the group consisting of C -C alkyl, C,,--C aryland alkaryl, C C halo-substituted aryl, and C C nitro-substituted aryl;but are preferably the same and are C,C alkyl or C -C aryl, morepreferably, C -C alkyl; and when R and R are taken together, they form abridge between the oxygen atoms, and may be C -C alkylene or C -Cphenylene, but are preferably C C, alkylene.

it is most preferred that R and R should be methyl and ethyl.

Suitable examples of R and R taken separately include: (a) methyl,ethyl, propyl, isopropyl, butyl, pentyl, octyl, decyl, pentadecyl,octadecyl, dodecyl, eicosyl, docosyl, and triacontyl; (b) phenyl,dimethylphenyl, xylyl and naphthyl; (c) 4-chlorophenyl, 3- bromophenyl,4-iodiphenyl, fluorophenyl, ochlorotoluyl, dichlorotoluyl,trichlorophenyl; (d) 2- nitrophenyl, 3-nitro-toluyl, 2-nitro-m-xylyl,2,5-dinitrom-xylyl; (e) 4-methylthiophenyl, methyl sulfonylphenyl; and(f) cyanophenyl.

Suitable examples of R, and R taken together include arylenes, such asphenylene and bivalent alkylenes represented by the formula C,,H,,,,wherein n is an integer of from 1 to 30, e.g., methylene, ethylene,propylene, octadecylene, etc. The alkylene group can be a nonbranchedpolymethylene unit or a branched alkylene moiety. The resultingheterocyclic ring is preferably five and six membered.

Some examples of suitable dihydrocarbyl monothiophosphoric acid addingagents include: dimethyl thiophosphoric acid, diisopropyl thiophosphoricacid, dioctyl thiophosphoric acid, ditriacontyl thiophosphoric acid,ethyl isopropyl thiophosphoric acid, trimethylene thiophosphoric acid,diphenyl thiophosphoric acid, dihexadecylphenyl thiophosphoric acid,dichlorophenyl thiophosphoric acid, dibenzyl thiophosphoric acid, ethylbenzyl thiophosphoric acid.

The monoadduct is prepared in significantly increased yields byutilizing a stoichiometric excess of the dihydrocarbyl-thiophosphoricacid. In order to realize this significant increase in monoadduct yield,the thiophosphoric acid should be employed in at least a 25 molarpercent excess over the stoichiometric amount required for monoadductformation. Preferably, however, a 50 to 200 percent excess should beemployed, although greater amounts of thiophosphoric acid, i.e., up to2,500 percent excess, may be satisfactorily employed.

The temperature at which the dihydrocarbyl thiophosphoric acid andmethylacetylene are reacted also varies over a broad range; and, ingeneral, is between about l00 C. and about +l00 C., preferably betweenabout 20 C. and about C., and more preferably at about room temperature,i.e., between about 16 C. and about 28 C. The reaction can also beperformed over a wide range of pressures, e.g., between about 0.1atmosphere and about atmospheres, but preferably is carried out underatmospheric or autogenous pressures.

The reaction to prepare the S-propenyl dihydrocarbyl thiophosphates maybe carried out in the presence of an inert diluent; however, it ispreferred that a diluent not be employed. Suitable diluents which may beemployed, if desired, include: C -C aliphatic hydrocarbons, C,,-Ccycloaliphatic hydrocarbons, ethers, and thioethers.

The free radical catalyst employed to initiate the reaction between themethylacetylene and the dihydrocarbyl thiophosphoric acid is, ingeneral, any of the organic or inorganic compounds which areconventionally employed as free radical initiators. In addition,non-chemical free radical initiators, such as ultraviolet light or gammairradiation and heat can be employed; ultraviolet light being preferred.

The source of ultraviolet light or gamma (X-ray) radiation is notcritical. A 70-watt high pressure mercury arc lamp, emitting light of awide spectrum wavelength, can be suitably employed in the laboratory;however, any source of ultraviolet light regardless of the quantity ofwattage can be used. Of course, the more intense the source, the fasterthe reaction proceeds. In the case of gamma irradiation, a 1,000 to10,000 Curie Co source is, for example, suitable to initiate theabovedescribed reaction from a distance of 6 cm.

With respect to the chemical free radical initiators, a wide variety oforganic peroxides, hydroperoxides, per-esters, per-acids andazo-compounds can be employed. Examples of suitable chemical freeradical initiators include: 2,4-dichlorobenzoyl peroxide, lauroylperoxide, methylethyl ketone peroxide, decanoyl peroxide, caproylperoxide, acetyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide,hydroxy heptyl peroxide, bis( l-hydroxycyclohexyl) peroxide, dicumylabout 5.0 mole percent, based on the total amount of reactants.

The S-propenyl dihydrocarbyl thiophosphates prepared in accordance withthe free radical catalyzed reaction described hereinabove, can bedepicted by the following formula:

R20 CH1 wherein R and R are hydrocarbon radicals as describedhereinabove with respect to the definition of the dihydrocarbylthiophosphoric acids.

Examples of the S-propenyl dihydrocarbyl thiophosphate intermediateproducts of the present application include: S-propenyl dimethylthiophosphate, S- propenyldiisobutenyl thiophosphate, S-propenyl dicetylthiophosphate, S-propenyl ditolyl thiophosphate, S-propenyl dinaphthylthiophosphate, S-propenyl dioctadecylphenyl thiophosphate, S-propenyldichlorobenzyl thiophosphate, S-propenyl ethyl benzyl thiophosphate.

In preparing the novel mixed diadducts of the present process, theS-propenyl dihydrocarbyl thiophosphate is reacted, in the presence of afree radical initiator, with an organic thiol. Organic thiols which canbe employed in the present process are represented by the followinggeneral formula:

wherein R: is selected from the group consisting of C C, alkyl, C.,-Caryl, C -C alkaryl, C,,--C aralkyl, halo-substituted C.,-C aryl andnitro-substituted C -C aryl. Preferably, R is a C -C5 alkyl, a C -Caryl', most preferably R is C -C alkyl.

Suitable examples of organic thiols include: methanethiol, ethanethiol,n-propanethiol,.isopropanethiol, nbutanethiol, benzenethiol,alpha-naphthalenethiol, otoluenethiol, alpha-toluenethiol,4-chlorob'enzenethiol, 4-nitrobenzenethiol, 3-chloro-p-toluenethiol,2,4- dichlorobenzenethiol and 4-methylmercaptobenzenethiol,phenylethanethiol.

The free radical reaction between the S-propenyldihydrocarbylthiophosphate and the organic thiol can be carriedout at a temperature of between about 80 C. and about +50 C., preferablybetween about 0 C. and about 40 C. When irradiation is employed toinitiate the reaction, the temperature preferably varies between about 0C. and about +30 C., and more preferably is performed at ambienttemperatures, i.e., between about 16 C. and about 28 C. The preferredtemperature range in the case of chemical initiators depends on thedecomposition temperature of the peroxidic compound utilized. Pressuresemployed are in general, atmospheric or autogenous; the latter up toabout 20 atmospheres.

The mole ratio of the organic thiol to the S-propenyldihydrocarbylthiophosphate can vary between about 1:1 and about 10:1. Anexcess of the organic thiol compound is preferred, i.e., molar ratios of2:1 to 10:1, e.g., 3:1.

The preparation of the mixed diadduct of the present process can becatalyzed by any conventional free radical initiator, both chemical andnon-chemical. Any of the free radical initiators and their amountsdescribed hereinabove with regard to the reaction between thedihydrocarbyl thiophosphoric acid and methylacetylene can be employed tocatalyze the reaction between the organic thiol and the S-propenyldihydrocarbyl thiophosphate.

Suitable diluents can be employed for the preparation of the novel mixeddiadducts of the present process and those described in connection withthe preparation of the S-propenyl dihydrocarbyldithiophos phates aretypical examples thereof. However, it is preferred not to use a diluentfor the preparation of the mixed diadduct.

The novel mixed diadducts of the present process can be represented bythe following formula:

R30 CH3 wherein R R and R are radicals as described hereinabove withrespect to the definition of the dihydrocarbyl thiophosphoric acids andthe organic thiols, respectively.

Some of the examples of the novel sequential diaducts include: dimethylZ-ethylthiopropyl thiophosphate, diethyl Z-methylthiopropylthiophosphate, ethyl propyl S-Z-methylthiopropyl thiophosphate, diethylS-Z-phenylthiopropyl thiophosphate, diethyl S-2-p-chlorophenylthiopropylthiophosphate, diethyl S-2-p-methylthiophenylthiopropyl thiophosphate,diethyl S-2-p-cyanophenylthiopropyl thiophosphate, ditriacontylS-2-p-dodecylphenylthiopropyl thiophosphate, ethyl benzylS-2-phenylthiopropyl thiophosphate, dibenzyl S-2-methylthiopropylthiophosphate, diphenyl S-2-dichlorobenzylthiopropyl thiophosphate,didodecylphenyl S-Z-phenylthiopropyl thiophosphate.

The new diadducts are useful as pesticides. Some of them are outstandingsystemic pesticides relatively safe to use. Others are contactinsecticides. A few of them, due to their low toxicity, have a highpotential for controlling animal insects. Of course, dependent on theirparticular structure, they possess different degrees of attractivenessfor the various useful applications. Various concentrations of thedifferent diadducts may be required as active ingredients in pesticidalcompositions to provide effective insect control.

For example, the particularly attractive sequential diadducts from theviewpoint of systemic plant insecticide applications are those having asignificant degree of solubility in water. Water solubility allows suchcompounds to be transported in the plant sap from the roots to theleaves. In terms of substituents this means that from this viewpoint themost desirable diadducts have their R R, and R, groups selected frommethyl and ethyl groups.

From the viewpoint of contact insecticidal and fungicidal activity onthe other hand one may wish to select aromatic radical substituents,particularly for R The novel mixed diadducts of the present inventioncan be employed as pesticidal compositions in either a solid or liquidform. When used in a solid form, they may be reduced to an impalpablepowder and applied as an undiluted dust or mixed with a solid carriersuch as clay, talc and bentonite, as well as other inert carriers knownin the art. The mixed diadduct can also be applied as a spray in aliquid carrier either as a solution in a solvent or in an emulsion in anonsolvent such as water. In the diluted solid or liquid form, the mixeddiadducts of the present invention can be employed in an amount ofbetween about 0.0001 and about 15.0 wt. percent, based on the inertcarrier. Typical liquid solvents include such compounds as acetone,ethyl alcohol, benzene, naphtha, etc. Suitable wetting agents andemulsifying agents can also be employed in preparing the pesticidalcompositions. The mixed diadducts of the present process can also beadmixed with carriers that are themselves pesticides. Finally, theactive compounds of the present invention can be used without dilutionas an atomized mist.

EXAMPLE 1 A mixture of 17 grams (0.1 mole) of 0,0-diethyl thiophosphoricacid and 2 grams (0.05 mole) of methylacetylene was irradiated withultraviolet light in a sealed quartz tube under its own vapor pressureat 17 C. for 40 hours. Semi-quantitative proton nuclear magneticresonance (NMR) analysis of the product mixture indicated 60 molepercent of 0,0'-diethyl S-( 1- propenyl) thiophosphate and no diadduct.The unreacted methylacetylene was removed under vacuum. The productmixture was then dissolved in ether and the unreacted acid removed bywashing with 5 percent aqueous sodium bicarbonate solution. Evaporationof the ether afforded 6.08 grams (57 percent) ofa tan liquid productwhich was 98 percent pure on gas liquid chromatographical (GLC)analysis. Fractional distillation yielded the pure product, b.p. 69.570(0.20 mm Hg), n 1.4756.

Anal. Calcd. for C H O SP: C, 40.00; H, 7.14; P, 14.76; S, 15.23. Found:C, 40.42; H, 7.21; P, 14.55; S, 15.15.

EXAMPLE 2 A mixture of 59.4 grams (0.3 mole) of 0,0- diisopropylthiophosphoric acid and 4.0 grams (0.1 mole) of methylacetylene wasreacted and worked up as described in Example 1. The crude product was ayellow liquid (16.26 grams, 68 percent yield) which contained 10 percentof diisopropyl hydrogen phosphite already present in the acid employed.Fractional distillation afforded 0,0-diisopropyl S-(l-propenyl)thiophosphate of 99 percent purity (GLC), b.p. 79-80 (0.40 mm Hg); n1.4651.

Anal. Calcd. for C H O Psz C, 45.36; H, 8.04; P, 12.99; S, 13.45. Found:C, 45.67; H, 8.39; P, 12.11; S, 13.45.

EXAMPLE 3 A mixture of 51 grams (0.35 mole) of 0,0'-dimethylthiophosphoric acid and 3.8 grams (0.96 mole) of methylacetylene wasirradiated for 87 hours as in earlier examples. A subsequent analysis byNMR indicated an approximate conversion of 32 percent. The correspondingamount of crude, neutral monoadduct was obtained after the removal ofthe unreacted acid with the procedure described in Example 1. Fractionaldistillation yielded 0,0'-dimethy1 S-( l-propenyl) thiophosphate of 96percent purity G L C as a colorless liquid boiling at 63-64 (0.3 mmHg.).

Anal. Calcd. for C H O PS: C, 32.96; H, 6.08; S, 17.54. Found: C, 33.02;H, 6.15; S, 17.61.

EXAMPLE 4 A mixture of 17 grams (0.1 mole) of 0,0-diethyl thiophosphoricacid and 4 grams (0.1 mole) of methylacetylene was reacted and worked upas described in Example 1. Fractional distillation afforded a product of0,0'-diethyl S-(l-propenyl) thiophosphate in 35 mole percent yield andno diadduct.

Additional reactions of equimolar amounts of 0,0- diethyland0,0-diisopropyl thiophosphoric acid with methylacetylene result inmonoadduct yields ranging from 35 to 40 mole percent. Thus, a comparisonof the results in Examples 1, 2, and 4 clearly show that excessmonothiophosphoric acid significantly increases the yield of themonoadduct, i.e., approximately 50 percent in Example 1 over Example 4,and approximately percent in Example 2 over Example 4.

EXAMPLE 5 A mixture of 34 grams (0.2 mole) of 0,0-diethyl thiophosphoricacid and 4 grams (0.1 mole) methylacetylene was heated in a sealed Pyrexpressure tube, at 50 C. for 24 hours. The tube was then opened at roomtemperature and evacuated down to a pressure of 40 mm to remove theunreacted methylacetylene. The residual contents were then dissolved in400 ml ether and washed with two 200 ml portions of a 5 percent aqueoussolution of sodium hydrogen carbonate to remove the unreacted acid. Theether solution was dried over sodium sulfate, filtered and evaporated.The neutral, residual product was then nitrogen purged at 0.1 mm for 2hours to remove all the ether. The resulting crude product was found tobe essentially 0,0'-diethyl S-( l-propenyl) thiophosphate by NMR. It wasobtained in an amount of 6.5 g., i.e., a yield of 31 percent. Ondistillation in vacuo from a bath of 100 C., 5 g. of the purifiedproduct, distilling at 50 (0.1 mm. Hg.) was ob tained.

EXAMPLE 6 A mixture of 4.2 grams (0.02 mole) of 0,0'-diethy1 S-(1-propenyl)-thiophosphate and 1 gram (0.021 mole) of a methyl mercaptanwas irradiated with ultraviolet light in a sealed quartz tube under itsown vapor pressure at 17 C. for 22 hours. Gas liquid chromatography ofthe crude reaction mixture indicated about percent conversion.Distillation in vacuo afforded a pure sample of the mixed diadduct, b.p.-102 C. at 0.15 mm. Hg. The adduct structure,

was verified by NMR analysis.

Anal. Calcd. for C H O S P: C, 37.21; H, 7.36; S, 24.80; P, 12.01.Found: C, 37.53; H, 7.72; S, 24.77; P, l 1.86.

EXAMPLE 7 A mixture of 2.1 grams (0.01 mole) of 0,0'-diethylS-(l-propenyl) thiophoshpate and 1.24 grams (0.02

mole) of ethyl mercaptan was irradiated for 15 hours as outlined inExample 4. Excess ethyl mercaptan was removed by vacuum. The residue,2.52 grams (97 percent yield), was greater than 95 percent pure mixedthe diadduct was 0,0'-diethyl S-l-methylthiopropyl thiophosphate.

In contrast to the S-Z-methylthiopropyl diadduct of Example 6, theS-l-methylthiopropyl product of the diaddllct, 5 present exampleunderwent the following thermal de- 1 composition on attempteddistillation at 0.1 mm. Hg. (C21[5O 2li s UI2 ?H Cm pressure with a ll0C. silicon bath:

0 S-Czlla (czngom scnsona oQ1r5o '1 s'11+ onsoin as verified by gasliquid chromatography and NMR l0 0 LINEN 0110111, analysis.

EXAMPLE 8 The starting reactant products of the product decompositionwere recovered. The adduct was condensed in A mixture Y "P P y p a dryice isopropanol trap, while the acid was colphate and methyl mercaptanwas reacted as described l d as a di ill (b 85 37 (1 1 mm, H in Example6 to yield the mixed d adduct- Both were identified by their NMRspectra.

oinomsoinuusom EXAMPLE H H (L113 The products of Examples 1, 3, and 6 to9 were each dissolved in acetone and dispersed in distilled waterEXAMPLE 9 with X-lOO emulsifier (alkyl aryl polyether alcohol) to I ivespray emulsions of various concentrations. Each of A mlxture of 1 ,grams(0'05 mole) of 'dlmethyl t hese emulsions were used in standardlaboratory insec- S-(l-propenyl) thlophosphate and 6.2 grams (0.1ticidal and miticidal tests as described hereinbelow. mole) of ethylmercaptan was 1rrad1ated for 67 hours. An NMR spectrum of the resultingmixture indicated INSECTICIDAL TESTS a complete conversion of thethiophosphate. The mixture was washed with aqueous sodium hydrogen car-Mexican Bean Beetle Tests Li a bean leaves bonate as d ib d i E l 1 to ild 1 1 5 g, (94 sprayed on the dorsal and ventral surfaces were offeredpercent) of neutral crude mix d di dd 0; m to ten larvae of the Mexicanbean beetle (late second tional distillation in vacuo 10 g. (82 percent)of puriinstill) for a 48-hour feeding p ri d- Th feeding rate fl dadduct, 9(). 91 15 mm, Hg), and mortality data were recorded as well asfoliage injury if any. The positive standards were 0.05 percent(ClhOhPSCIIzCIISCzlI; DDT and 0.1 percent methoxychlor, respectively.

P, i Pea Aphid Tests Adult pea aphids were sprayed and transferred tosprayed pea plants and held for 48- was b i hour mortalitydeterminations. Foliage injury, if any, A l, (j d f C H O PS C, 3441; H7,01 s was recorded. DDT at 0.05 percent concentration was 26.25. Found:c, 34.60; H, 7.03; s, 26.20 used as the positive Standard- Systemicinsecticidal activity was evaluated by apply- EXAMPLE 10 ing 20 ml.spray of the sample to the vermiculite sub- To 4.5 grams (0.05 mole) ofmethyl S-(l-propenyl) stratum of potted pea plants. Forty-eight hoursafter lfid 85 grams (0,05 l f 0,()'-di th thioapplication the plantswere infested with 10 adult pea h h i id was dd d d i i h ti i A aphidsand mortality determination was made after 5 mildly exothermic reactionstarted to take place as iny D m t n at 101 percent concentration wasused dicated by a rise of the mixtures temperature to 35 C. as the p i iStandard. during the addition. After 3 days standing at room tem-Miticidal Tests Spider Mite Tests Lima bean perature, the mixture wasdissolved in 100 ml. of ether Plants were infested with to 100 adults ofthe strawd extracted i h t 25 l, ti f 5 percent berry spider mite,Tetranychus atlanticus, prior to testaqueous N flco l ti t remove thunrea ted 50 ing. The infested plants were dipped into the test mate:acid, After drying the solution over Na SO, and removrial and held for 5days. Adult mortality as well as oviing the vo|ati1es i vacuo 1 h at 1 8g (66 cidal action was noted. Aramite and Ovotran were used percent) ofthe slightly yellow mobile liquid mixed as positive standards at 0.1percent concentration. diadduct remained. Analysis by NMR establishedthat The results of the various tests are shown in Table I.

TABLE I Active ingredient Mortality of insects and mites alter test,percent Mex. beau beetles Pea aphids Spider mites C0nc., ContactSystemic Contact Systemic Contact Systemic Example No. Structure percent48 hours 5 days 48 hours 5 days 5 days 48 hours 1 (C2H5O)QPSCH=CHCHJ0.010 100 100 0 100 o 100 0.005 100 100 0 10 0 100 a (CIIQO)ZPSCII=CHCH;0.010 100 100 0 100 H 0.005 100 100 so 100 0 100 6 (Cz1I O)zPSCHzCIISCH30.010 100 100 100 100 i 0. 005 10 100 100 100 100 100 TABLE I-CominuedActive ingredient Mortality of insects and mites after test, percentMex. bean beetles Pea aphids Spider mites Conc., Contact SystemicContact Systemic Contact Systemic Example No. Structure percent 48 hoursdays 48 hours 5 days 5 days 48 hours 7 (CqlI O)zP S (3112C II S CaHr 0.010 100 100 100 100 100 100 H OH; 0.005 90 100 100 100 100 100 s(CIIgOhlSCHzCHSCH; 0.010 100 100 S2 100 c H; 0. 005 100 100 is 100 u(CI-I O)P S CHzC HS CzH5 0. 010 100 100 100 100 66 100 (EH; 0. 005 20100 100 100 48 100 The data of Table I show that the novel sequential tobe active against the bed bug (Cimer Lecturalius L) diadducts of thepresent invention are more effective pesticides against aphids and mitesthan the corresponding monoadducts. The systemic insecticidal andmiticidal effectiveness of the present diadducts is particularly high.

EXAMPLE 12 The products of Examples 69 were tested as emulsions ofvarious concentrations against the cotton boll weevil, mosquito larvaeand corn rootworm.

Contact and systemic tests on the cotton boll weevil were carried out ina manner analogous to the aphid tests described in the previous example.

Tests on the yellow fever mosquito, Aedes Egypti, used the apparatus forinsecticide assay described in the Journal of Economic Entomology, Vol.53, page 483, in 1960. Twenty-five 4th instar larvae were placed inbeakers containing 50 ml. of distilled water. One hundred and fifty mls.of each formulation was added to a beaker containing the mosquitolarvae. The larvae were held for 24 hours for mortality observations.These observations were made with the device referred to under testapparatus.

Adult Northern corn rootworms were collected from a field. The beetleswere placed on 5 percent sugar solution prior to and after treatment.The samples were dissolved in acetone and applied by means of amicroapplicator to the tip of the abdomen of each beetle. Dosages areindicated in the results. The tests were conducted in duplicate, l0insects per replicate. One microliter of the test emulsion was appliedper insect. Mortalities were recorded after 24 hours.

The results of the tests are summarized in Table II.

TABLE II in residual tests, the German cockroach (Blatella Germanica L)in contact spray test, fruit flies in Hawaii in spray tests and as alouse toxicant.

EXAMPLE 13 In order to determine the range of toxicity of the compoundsprepared in accordance with the present process, various calculateddoses of the adducts of methylacetylene were injected via a stomachsyringe into adult male mice of the Swiss Webster strain, 30-35 grams inweight. These mice were observed for survival during a two week period.On the basis of the mortality data, the range of acute oral medianlethal concentrations, LD s were estimated. The results are given inTable III.

The data of Table III show that the sequential diadducts of the presentinvention are surprisingly less toxic to warm-blooded animals than themonoadducts from which they are derived. The data also show that thesequential diadduct of Example 6 has an LD about 50 times higher thanthat of the structurally closely related Thiol-Systox. In other words,our diadduct is about 50 times safer to use than the active isomer ofthe commercial Systox pesticide.

What is claimed is:

l. A process for preparing sequential diadducts of methylacetylene whichcomprises the steps of l adding one mole of a thiophosphoric acidrepresented by the formula:

Cotton boll weevil Mosquito larvae,

Active ingredient mortality, percent percent Corn rootworm Conc., Conc.,Mortality, Example No. Structure percent Contact Systemic Cone.Mortality meg. n-l. [)i'i'PPlll.

6 (C:II50)2PSCII2CIISCH3 0.0020 82 2,5 190 g I 1. o .m

7 (C2 I50)2I?SCIIQCIiSCIIflh 0. 05 0.0020 100 1.0 mi; 1.) (I;IIJ u. I00

8 (ClI OhI S CIIZCII S CH; 0. U5 H0 0. 0020 4 V n 9 (CH O)zPSCH CHSCzII50.05 20 100 The data show that the mixed diadducts are active 65 againstthe insects tested.

in addition to the above, the product of Example 7, 0,0'-diethylS-2-methylthiopropyl thiophosphate, was tested by the AgriculturalResearch Service of the US. Department of Agriculture. The compound wasfound wherein each of R and R is selected from the group consisting of C-C alkyl, C -C aryl or alkaryl,

C -C halo-substituted aryl, and C C nitro-substituted aryl tomethylacetylene to form a monoadduct, S-propenyl thiophosphate, and (2)reacting said monoadduct with TABLE III Experimental compound(reference) Mortality, Estimated Example No. Structure Dosage, No. dead]D 0, rngJlrg. No. dosed ing./kg

1 (C2H50)zPSCH=CHCH 1 0 3 (CH3O)zPSCH=CHCH; 25 0/2 6 (CzHsOhPSCHzCHSCzHg50 0/2 9 (CH3O)PSCHOHSCH 50 0/2 (Thiol-Systox) (CzH5OhfiSCHzCHzSCzH5 1.5

a Expressed as mg. active compound per body kg. test animal. Publishedon page 343 of the Schrader monograph as acute oral median lethal dosefor rats.

an organic thiol represented by the formula methylacetylene.

2. The process of claim 1 wherein the molar ratio of organic thiol toS-propenyl thiophosphate is about 1:1 to 10:1.

3. The process of claim 1 wherein the first step to form a monoadduct iscarried out using a 50 percent to 200 percent excess of thiophosphoricacid above the 4. The process of claim 1 wherein the reactiontemperature of both steps is between C. to about +50 C.

5. A process for preparing mixed diadducts of methylacetylene whichcomprises reacting an S-propenyl thiophosphate represented by theformula R20 CH wherein each of R and R is C -C alkyl, with an organicthiol represented by the formula wherein R is C -C alkyl, in thepresence ofa free radical initiator at temperatures ranging from about-80 C. to about +50 C.

2. The process of claim 1 wherein the molar ratio of organic thiol toS-propenyl thiophosphate is about 1:1 to 10:1.
 3. The process of claim 1wherein the first step to form a monoadduct is carried out using a 50percent to 200 percent excess of thiophosphoric acid above themethylacetylene.
 4. The process of claim 1 wherein the reactiontemperature of both steps is between -80* C. to about +50* C.
 5. Aprocess for preparing mixed diadducts of methylacetylEne which comprisesreacting an S-propenyl thiophosphate represented by the formula